//MyThis.java
package com.xyc.mythis;
class Cat
{
	//private int age=0;
	Cat grow()
	{
		age++;
		return this;
	}
	private int age=0;
	void print()
	{
		System.out.println("Cat is "+age+"years old");
	}
}
public class MyThis1
{
	public static void main(String[] args)
	{
		Cat cat=new Cat();
		cat.grow().grow().grow().grow().print();
	}
}